The assembly of a book with a hard or flexible cover requires several distinct operations. The body of the book must first be collated into a book block to provide for proper pagination of the text. Then, endsheets are attached to the book block by methods such as adhesive binding, "Smyth" sewing, side sewing, side wire stitching or saddle stitching. The bound book block is then trimmed on three sides to provide the final size.
The book block backbone, or spine, is then reconfigured to a specific configuration such as a flatback without joints, a flatback with joints, a round configuration only, or a round configuration with joints. To retain the selected shape placed into the backbone of the book, an adhesive is typically applied followed by the application of a reinforcing woven material. This may be followed by a film of adhesive to which a liner with head bands is applied. Lastly, the book is completed by joining the endsheets to the cover.
As stated previously, numerous adhesives, such as hot melt adhesives, have been applied to the spine of the book block. This can be accomplished by an adhesive extrusion process or by running a fixed wheel through a bath of hot adhesive which then applies the adhesive to the book binding. An exemplary system which performs such a function is described in U.S. Pat. No. 5,194,116 to Davis et al. However, utilizing a hot melt adhesive to attach the cover to the endsheets is not known to have been performed.
Generally, the cover is attached to the endsheets by use of a water-based or an emulsion adhesive. A emulsion adhesive is one which has aqueous components and oil components. However, once any water is placed upon the endsheets, the first and last pages of the book back adjacent the endsheet may become exposed to the water. This is especially true if the pages of the book back have been exposed to a high temperature, low humidity atmosphere to dry the pages after ink has been applied. In this situation, the dry pages tend to pull the water from the endsheets. If the pages become wet, they become wrinkled when dried. In some situations, the aesthetically undesirable book must be scrapped or sold at a reduced cost since it is a defective product.
On the other hand, if an oil-based adhesive is used, water is not present and the likelihood of any wrinkles on the first and last pages of the book block is drastically reduced. Several systems exist which allow for the use of hot melt adhesives; but these systems have distinct disadvantages. For example, the appropriate temperature must be constantly maintained. Otherwise, application inconsistencies will occur due to the change in viscosity arising from the temperature variances. If the temperature is too hot, stringing of the adhesive can occur. If the temperature is too cold, then the adhesive tends to coagulate. Irregularity in the viscosity may even change through one application where the beginning of the run is adequate while the end of the run is inadequate. The change in temperature of the adhesive results from convection into the ambient environment which can vary a great deal in manufacturing facilities.
It would be advantageous to have a method in which endsheets could be attached without moisture wrinkle on the pages of the book block. Also, it would be desirable to have a machine available that could apply hot melt adhesives at approximately a constant temperature to the endsheet of the book block to overcome the application problems associated with hot melt adhesives. Such a machine would then achieve the desirable no-wrinkle result when used with a hot melt, oil-based adhesive.